Workpiece guide for sewing machine

ABSTRACT

A sewing machine has a sewing surface along which the workpiece is passed through a sewing station. A fixed guide element has a guide edge extending parallel to the workpiece path next to the station. A cover element is spaced above the surface and is displaceable between an operative position overlying the path and overhanging the guide edge to define with this guide edge and with the sewing machine working surface a guide slot, and an inoperative position lying outside the path in back of the guide edge. A pneumatic cylinder is provided to displace this cover element between these two positions and is coupled to the sewing machine drive so that the cover element is in its operative position when the machine is operating at high speed but is displaced into an inoperative position when the machine is operated at low speed for precise stitching.

United States Patent Pollmeier WORKPIECE GUIDE FOR SEWING MACHINE [75] Inventor: Konrad Pollmeier, Bielefeld,

Germany [73] Assignee: Durkoppwerke GmbII, Bielefeld,

Germany [22] Filed: May 20, 1974 [21] Appl. No.: 471,645

[30] Foreign Application Priority Data May 23, 1973 Germany 7319362[U] [52] U.S. Cl. 112/153 [51] Int. Cl D05b 35/10 [58] Field of Search ..112/153,152,l36,121.1l

[56] References Cited UNITED STATES PATENTS 2,761,401 9/1956 Dolney 112/152 3,752,100 8/1973 Sharp 112/153 Primary Examinerll. Hampton Hunter Attorney, Agent, or Firml(ar1 F. Ross; Herbert Dubno [57] ABSTRACT A sewing machine has a sewing surface along which the workpiece is passed through a sewing station. A fixed guide element has a guide edge extending parallel to the workpiece path next to the station. A cover element is spaced above the surface and is displaceable between an operative position overlying the path and overhanging the guide edge to define with this guide edge and with the sewing machine working surface a guide slot, and an inoperative position lying outside the path in back of the guide edge. A pneumatic cylinder is provided to displace this cover element between these two positions and is coupled to the sewing machine drive so that the cover element is in its operative position when the machine is operating at high speed but is displaced into an inoperative position when the machine is operated at low speed for precise stitching.

10 Claims, 2 Drawing Figures Eli SEW/N6 I l U.S. Patent Oct. 21, 1975 I ll 14 32 III I IHUL WORKPIECE GUIDE FOR SEWING MACHINE FIELD OF THE INVENTION The present invention relates to a workpiece guide fora sewing machine.

BACKGROUND or THE INVENTION In the manufacture of clothing and the like it is known to provide a fixed guide edge next to the stitching stations of a sewing machine. The workpiece to be stitched is guided along the surface of the sewing machine and passed through the stitch station with the edge of the workpiece riding against the guide edge. Such a guide edge thereby insures that the line of stitching produced lies at a predetermined distance from the edge of the goods.

In the production of goods such as stockings it is frequently desirable to provide a workpiece holddown in front of the stitching station along the workpiece path to flatten the workpiece before it is fed into the stitching station. Such a holddown is generally formed as a plate extending outwardly from the guide edge. It serves in addition to prevent the goods being stitched from riding up over the guide edge or from bunching at the sewing station.

The principal disadvantage of such a workpiece guide or holddown is that a seam or thick part of the goods can become caught under the holddown. Thus it is necessary to space the holddown above the working surface at a distance large enough to pass the goods at their thickest. This large spacing at least partially defeats the purpose of the holddown, as the material is not pressed against the workpiece table immediately upstream of the sewing station.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide an improved sewing machine.

Yet another object is the provision of an improved workpiece guide for a sewing machine.

yet another object is to provide such a workpiece guide which overcomes the above-given disadvantages.

SUMMARY OF THE INVENTION These objects are attained according to the present invention in a workpiece guide comprising a fixed guide element having a guide edge extending along the workpiece path adjacent the sewing station, and a cover plate which is spaced above the surface and is displaceable between an operative position overlying the path and overhanging the guide edge to define therewith and with the surface a guide slot for the workpiece, and in operative position lying outside the path and in back of the guide edge, that is on the other side of the guide edge from the sewing station. Means is provided to displace the cover plate between the operative and inoperative position.

Such an arrangement allows the holddown plate or cover element to be spaced relatively closely to the sewing surface whenever precise guiding of the workpiece is necessary, while when a thickened portion of the workpiece, such as the hem or foot of a stocking,

must pass through the stitching station this cover element is displaced out of the workpiece path, thereby allowing maneuvering of the workpiece by hand.

In accordance with other features of this invention the sewing machine has a two-speed drive, allowing it to be operated at a relatively fast running speed and a relatively slow precision-sewing speed. The actuating means for the cover element is connected to this twospeed drive so as to hold the cover element in the operative position when the machine is operating at high speed and inoperative position when operating at low speed, thereby automatically displacing the cover element out of the workpiece path when precise stitching must be made.

According to yet another feature of this invention there is provided in the workpiece path upstream of this sewing station a sensor which detects the thickened area of the workpiece and automatically displaces the cover element frrom the operative to the inoperative position.

In accordance with this invention the guide element having the guide edge is a metal plate secured to the sewing machine working surface, and the cover element is a pivoted metal plate lying on top of the guide element and defining therewith a guide slot having a thickness approximately equal to that of the guide element. This cover element is pivoted on the guide element and is operated in accordance with this invention by'its own small pneumatic cylinder.

In accordance with yet another feature of this invention means is provided for displacing the cover element and guide element transversely to the workpiece path and toward and away from the sewing station. This allows the seam spacing from the edge of the workpiece to be adjusted.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects, features, and advantages will become more readily apparent from the following, reference being made to the accompanying drawing, in which:

FIG. 1 is a top view partly in diagrammatic form of the arrangement according to the present invention, and

FIG. 2 is a side view taken in the direction of arrow ll of FIG. 1.

SPECIFIC DESCRIPTION As shown in FIG. 1 a sewing machine has sewing table or surface 1 to which is secured as also shown in FIG. 2 a bottom guide plate 10 having a guide edge 11 turned toward a sewing station S. Goods to be stitched are fed to the station S in a path generally indicated by arrow P and parallel to a section 1 ll of the guide edge 1 l.

The sewing station S is provided with a vertically reciprocal needle 7 adapted to be received in a hole 5 in the surface 1. Conventional feed pads 4 are provided for advancing the workpiece in the direction of arrow P and a presser foot 8 is adapted to hold the workpiece down on these feeders 4. A two-speed sewing machine drive 9 serves to operate the needle 7 and feeders 4.

Pivoted on a bolt 25 welded to the plate 10 is a cover plate 20 having a foot 23 which can overhang the edge 11 over top of the path P and define a guide slot 12 adapted to snugly receive the workpiece.- Another plate 30 overlies the plate 20 and is secured via bolts 3 passing through slots 2 perpendicular to the path P. These bolts 3 also secure the plate 10 to the surface 1, this plate 10 being similarly formed with slots 2 so as to allow the entire arrangement to be displaced in the direction of double-headed arrow a shown in FIG. 1. A

nut 31 on top of the pivot bolt 25 for the plate overlies plate 30.

The plate 20 is provided with an actuating arm 22 formed at its end with a slot 24 in which a pin 63 carried on a fork 62 in turn on the piston rod 61 of a pneumatic cylinder 6 serves to displace the foot 23 between the solid-line position and the dot-dash position shown in FIG. 1. This cylinder 6 is carried on a flange 17 bent up from the plate 30.

A compressor 13 is connectable via a valve 14 to the cylinder 6, which is itself urged by an internal spring into the solid-line position of FIG. 1. Opening of the valve 14, as for example by a foot switch 15, causes the cylinder to push the arm 22 and swing the cover plate 20 behind the guide edge 11. This allows a thicker part of the workpiece to pass through the stitching station S. Advantageously this foot pedal 15 is also connected to the two-speed drive 9 so that on normal runs which can be sewn at high speed the cover plate is in the operative, solid-line position but when a difficult region must be stitched the pedal 15 is depressed to swing the cover plate 20 out of the way and simultaneously slow down the sewing speed.

Sensor 16 is also provided upstream of the sewing station S so as to detect the thick part of the workpiece and operate the valve 14, thereby automatically swinging the cover plate 20 out of the way. Such a sensor 16 in use in a machine for stitching stocking or hosiery can comprise a photocell which detects the thick dark regions of the foot and waistband of hose. In addition such a sensor 16 may slow down the drive 9 as described above.

The guide edge 1 1 comprises the straight section 1 l 1 next to the sewing station S and a curved section 211 upstream or in front of the station S and curved away from an imaginary line L running parallel to the path P and lying on the section 111.

Such an arrangement increases production speed considerably as the workpiece is precisely guided whenever that is possible, but where for some reason it is impractical to have the guide in place, it can readily be moved out of the way to allow the workpiece to be fed by hand.

I claim:

1. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising:

a guide element fixed to said surface and having a guide edge extending along said path adjacent said station;

a cover plate spaced above said surface, overlying said guide element and overhanging said edge in an operative position of overlying said path to define therewith and with said edge a guide slot for said workpiece,

means pivotally mounting said cover plate for swinging movement about an upright axis relative to said guide element from said operative position into an inoperative position wherein said cover plate lies wholly outside said path to the side of said edge op posite said station; and

means for displacing said cover plate between said positions.

2. The guide defined in claim 1 wherein said guide edge is generally vertical and perpendicular to said surface, said cover plate being generally parallel to said surface.

3. The guide defined in claim 2 wherein said guide element is a flat plate secured to said surface.

4. The guide defined in claim 3, further comprising means for securing said flat plate to said surface and for permitting limited displacement of said flat plate and said cover plate toward and away from said station.

5. The guide defined in claim 3, further comprising a pivot in said flat plate for said cover plate.

6. The guide defined in claim 1 wherein said means is a fluid ram carried on said guide element.

7. The guide defined in claim 6 wherein said ram is a pneumatic cylinder.

8. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising:

a guide element fixed to said surface and having a guide edge extending along said path adjacent said station;

a cover plate spaced above said surface and overlying said guide element, said cover plate being displaceable between an operative position overlying said path and overhanging said guide edge to define therewith and with said surface a guide slot for said workpiece, and an inoperative position lying outside said path to the side of said edge opposite said station; and

means for displacing said cover plate between said positions said sewing machine having a two-speed drive for sewing said workpiece and selectively advancing said workpiece through said station at a fast rate and at a slow rate, said guide further comprising means connected to said means for displacing and operating same to position said cover plate in said operative position on operation of said machine at said fast rate and for automatically positioning said cover plate in said inoperative position of said machine at said slow rate.

9. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising: a guide element fixed to said surface and having a guide edge extending along said path adjacent said station;

a cover plate spaced above said surface and overlying said guide element, said cover plate being displaceable between an operative position overlying said path and overhanging said guide edge to define therewith and with said surface a guide slot for said workpiece, and an inoperative position lying outside said path to the side of said edge opposite said station;

means for displacing said cover plate between said positions; and

sensing means upstream in said path from said station for detecting an increase in thickness of said workpiece and connected to said means for displacing and operating same to automatically position said cover in said inoperative position on detection of such an increase in thickness.

10. The guide defined in claim 9 wherein said sensing means includes a photoelectric cell. 

1. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising: a guide element fixed to said surface and having a guide edge extending along said path adjacent said station; a cover plate spaced above said surface, overlying said guide element and overhanging said edge in an operative position of overlying said path to define therewith and with said edge a guide slot for said workpiece, means pivotally mounting said cover plate for swinging movement about an upright axis relative to said guide element from said operative position into an inoperative position wherein said cover plate lies wholly outside said path to the side of said edge opposite said station; and means for displacing said cover plate between said positions.
 2. The guide defined in claim 1 wherein said guide edge is generally vertical and perpendicular to said surface, said cover plate being generally parallel to said surface.
 3. The guide defined in claim 2 wherein said guide element is a flat plate secured to said surface.
 4. The guide defined in claim 3, further comprising means for securing said flat plate to said surface and for permitting limited displacement of said flat plate and said cover plate toward and away from said station.
 5. The guide defined in claim 3, further comprising a pivot in said flat plate for said cover plate.
 6. The guide defined in claim 1 wherein said means is a fluid ram carried on said guide element.
 7. The guide defined in claim 6 wherein said ram is a pneumatic cylinder.
 8. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising: a guide element fixed to said surface and having a guide edge extending along said path adjacent said station; a cover plate spaced above said surface and overlying said guide element, said cover plate being displaceable between an operative position overlying said path and overhanging said guide edge to define therewith and with said surface a guide slot for said workpiece, and an inoperative position lying outside said path to the side of said edge opposite said station; and means for displacing said cover Plate between said positions said sewing machine having a two-speed drive for sewing said workpiece and selectively advancing said workpiece through said station at a fast rate and at a slow rate, said guide further comprising means connected to said means for displacing and operating same to position said cover plate in said operative position on operation of said machine at said fast rate and for automatically positioning said cover plate in said inoperative position of said machine at said slow rate.
 9. A workpiece guide for a sewing machine wherein the workpiece is passed on a sewing surface along a path through a stitching station, said guide comprising: a guide element fixed to said surface and having a guide edge extending along said path adjacent said station; a cover plate spaced above said surface and overlying said guide element, said cover plate being displaceable between an operative position overlying said path and overhanging said guide edge to define therewith and with said surface a guide slot for said workpiece, and an inoperative position lying outside said path to the side of said edge opposite said station; means for displacing said cover plate between said positions; and sensing means upstream in said path from said station for detecting an increase in thickness of said workpiece and connected to said means for displacing and operating same to automatically position said cover in said inoperative position on detection of such an increase in thickness.
 10. The guide defined in claim 9 wherein said sensing means includes a photoelectric cell. 